Question

The number of moles of oxygen found in 82 g of sodium phosphate [Na3PO4] is
(Na = 23, P = 31 , O = 16)

(a) 0.5 mol
(b) 3mol
(c) 4 mol
(d) 2mol

Answer 1

$\fbox{ANSWER </p><p></p><p> Molecular weight of \oxygen is 32.</p><p></p><p>Thus the number of moles present is \ 16 g of O2 will be 0.5</p><p></p><p>Number of molecules present will be 0.5NA</p><p></p><p>Number of gram atoms will be 0.5×2NA=NA( Since one molecule of oxygen contains 2 atoms of oxygen)</p><p></p><p>1 mol of a gas occupies 22.4l at STP, thus given sample will occupy 11.2l at STP.</p><p></p><p>No. of protons=No.of gram atoms×8=8NA(Since one oxygen atom contains 8 protons)</p><p></p><p>}$